非血红素铁超氧化物活化丙烯分子多态反应机理的理论研究（英文）  

Theoretical Investigation on the Multi-State Reaction Mechanism for the Propene Catalyzed by Non-Heme Ferric-Superoxo Species

作　　者：吕玲玲[1] 朱元成[1] 左国防[1] 袁焜[1] 王永成[2] 

机构地区：[1]天水师范学院化学工程与技术学院 [2]西北师范大学化学化工学院

出　　处：《无机化学学报》2017年第2期329-339,共11页Chinese Journal of Inorganic Chemistry

基　　金：国家自然基金(No.21263022;21663025;2163024);甘肃省教育厅导师基金;天水师范学院"青蓝"人才工程基金资助项目

摘　　要：采用密度泛函DFT-B3LYP理论对非血红素铁超氧化物活化丙烯分子多态反应机理进行了探讨.研究结果表明氢原子抽取过程遵守单态反应机制,主要在基态高自旋七重态势能面进行,且具有较低活化能(ΔG~≠=65.6 k J·mol^(-1)),非血红素铁超氧化物可以作为有效氧化剂抽取氢原子。单态反应机制可能归因于近来建议的交换-加强反应原则(EER,铁中心具有较大交换稳定作用)。对于O-O键的活化,在CASSCF(10,8)/6-31+G(d)//TZVP水平下,势能面交叉区内,高自旋七重态(S1)和五重态(Q0)的自旋-轨道耦合(SOC)常数分别为2.26和2.19 cm^(-1)。轨道分析表明两条发生翻转自旋轨道具有相同空间组成(π*sub),SOC禁阻,因此通过SOC作用反应体系不可能有效地从七重态(S=3)势能面系间穿越到五重态(S=2)势能面,系间穿越可能发生在反应最后的退出阶段。The multi-state reaction mechanism for the propene catalyzed by non-heme ferric-superoxo model complex has been investigated at the DFT-B3LYP level. The calculations show that non-heme ferric-superoxo complex can be considered as effective oxidants in hydrogen atom abstraction reaction （single-state-reactivity）, for which we find a lower barrier of ΔG^≠=65.6 kJ·mol^-1 on the septet spin state surface. Single-state-reactivity is possibly due to the recently proposed exchange-enhanced reactivity （EER）principle with larger exchange stabilization of the Fe center. For the O-O bond activated step, we computed the spin-orbit coupling （SOC）constants of the septet, S1 and quintet, Q0 state at the crossing region and found it to be 2.26 and 2.19 cm^-1 at the CASSCF （10, 8）/6-31＋G （d）//TZVP levels, respectively. Orbital analysis show that two spin orbitals have the same spatial component in their wave functions （π＊sub）, therefore, the S=3 surface cannot effectively intersystem cross to the S=2 surface through the SOC interactions,and the intersystem crossing is possibly occurred at the exit stage of the reaction.

关 键 词：非血红素铁超氧化物 多态反应机理 系间窜越 自旋轨道耦合 

分 类 号：O641.121[理学—物理化学]